发酵条件对泡菜发酵过程中微生物菌系的影响

研究了初始食盐浓度、发酵温度、花椒和碘对自然发酵泡菜液中微生物菌系的影响。研究表明,在较高温度下发酵,不利于乳酸菌形成生长优势;在较低温度下发酵,6 %的盐浓度比8%的盐浓度能更好地促进乳酸菌的生长;花椒和碘可使参与发酵的主要菌群乳酸菌和酵母菌加快生长和繁殖。     

罗汉果在乳酸菌发酵食品泡菜中的应用研究

以包心芥菜和胡萝卜为原料,两者比为3:2,添加罗汉果水煎汁,采用正交实验方法制作泡菜,并结合泡菜中乳酸菌数及维持高含菌量的时间,得出最佳工艺条件为:罗汉果汁量4%、盐浓度4%、糖浓度1%、接种量3%、发酵温度30℃,发酵时间5d.根据此条件,开发出了具有消暑止渴、清热解毒、止咳化痰等功效的新型泡菜保健食品.     

辣椒酱发酵工艺研究

辣椒酱发酵合适的工艺参数为发酵液用量5%、发酵时间6d、盐浓度3%、糖浓度2%。发酵6d后,含酸量达到0.59%。纯菌种发酵过程中亚硝酸盐最高含量为0.64mg/kg,而自然发酵时可达6.12mg/kg。杀菌温度90℃杀菌时间5min。     

食盐浓度对传统四川泡菜发酵过程中乳酸菌菌相的影响

研究了萝卜、白菜、豇豆3种蔬菜原料的泡菜自然发酵过程中,不同盐浓度对乳酸菌数量及产酸量的影响,以及在6%食盐浓度下,采用新老泡菜水泡制3种蔬菜的乳酸菌群变化。结果表明6%的盐浓度最适宜3种蔬菜的乳酸发酵,在同一盐浓度6%新盐水中,乳酸发酵的速度白菜>萝卜>豇豆;在6%的老盐水中,3种蔬菜发酵速度差异不明显。从3种发酵蔬菜泡菜水分离鉴定共得到6株革兰氏阳性菌株,其中4株为食窦魏斯氏菌(Weissella cibaria),1株为柠檬明串珠菌(Leuconostoc citreum),1株为植物乳杆菌(Lactobacillus plantarum)。四川泡菜生产宜充分考虑原材料差异性及利用老盐水优势性。     

食盐对混合菌种发酵香肠质量指标的影响

研究盐浓度对香肠中pH、亚硝酸盐、TVB-N、以及微生物等安全指标的影响,确定最适腌制盐浓度。结果表明:在1.5%及2.0%的盐浓度下乳酸菌受到的抑制作用较小,且发酵开始后的前6h数量增加较快,6h后数量上升缓慢;当盐浓度达到2.5%~3.0%时,乳酸菌的生长繁殖受到一定程度的抑制;盐浓度达到2.0%~3.0%时,大肠菌群的生长繁殖受到明显抑制;盐浓度对菌落总数影响最大,盐浓度在1.5%~3.0%时,随着盐浓度的升高,发酵6~9h后的总菌落数明显降低。盐浓度也影响发酵香肠pH值的变化,低盐度(1.5%~2.0%)条件下pH值下降更快。在1.5%~3.0%的盐浓度下,发酵6~9h后香肠的亚硝酸盐含量随盐浓度的增加而增加。同时随着发酵时间的延长而增加;此外,TVB-N的含量显然也受到盐浓度的影响。采用2.0%~2.5%的食盐腌制的益生菌发酵香肠具有较好的亚硝酸盐及微生物学安全性。     

乳酸片球菌液态法发酵猪肉的工艺研究

研究了乳酸片球菌液态法发酵猪肉的生产工艺.对影响发酵的因素 --盐浓度、亚硝酸钠浓度、接种量、发酵时间和发酵温度等进行优化实验研究,通过正交试验,得到盐浓度2.5%、亚硝酸钠浓度 0.012%、接种量 3.5%、发酵时间 21h、发酵温度 30℃的优化发酵工艺条件.优化发酵条件下所得产品,微生物及NaNO 2含量均达到标准,具有良好的发酵肉风味,结果令人满意.     

响应面法优化马奶酒发酵条件的研究

以新鲜马奶为原料,通过考察接菌量(乳酸菌/酵母菌)、发酵温度、发酵时间、糖添加量单因素试验对马奶酒发酵的影响,并借助响应面设计,研究接菌量(乳酸菌/酵母菌)、发酵温度、发酵时间对马奶酒品质的影响。结果表明,最佳发酵条件分别为接菌量(乳酸菌/酵母菌)3%∶5%、发酵温度32℃、发酵时间80h、糖添加量6%。马奶酒酒香清雅,微酸爽口。     

锦州腌渍小菜中耐盐乳酸菌的筛选与产酸性能研究

从锦州腌渍小菜中分离获得28株耐盐性乳酸菌,对其在不同盐浓度条件下产酸能力进行分析,结果表明,从初步鉴定的20株乳酸菌中筛选出6株菌株,最终得到高产耐盐乳酸菌菌株L7。采用正交试验方法优化试验条件,结果发现选择提供乳糖为碳源,大豆蛋白胨为氮源的生长环境,发酵时间为20h,发酵温度为32℃,盐浓度为7%在此条件下菌株L7的产酸能力可由1.48%提高至1.60%。耐盐产酸性能的优良菌株筛选为改善锦州腌渍小菜的品质具有一定的理论和应用价值。     

酵母和乳酸菌发酵生产白啤酒研究

以 6 0 %大麦芽和 4 0 %小麦芽为原料 ,经上面酵母和乳酸菌L4混合发酵 ,研制生产出白啤酒。从 4株乳酸菌中筛选出适合白啤酒生产的L4菌 ,通过对发酵方式的选择 ,确定了酵母BLS 1和乳酸菌L4混合发酵方式 ,同时对酒花添加量、接种量及发酵温度和时间进行了讨论 ,制定出工艺路线 ,所得白啤酒质量符合标准。     

自然发酵条件下西瓜翠衣泡菜的研制

为研究西瓜翠衣泡菜自然发酵的工艺,该文以西瓜翠衣为原料,对其发酵工艺参数进行探究。通过单因素和响应面试验研究盐浓度、糖浓度及发酵温度对西瓜翠衣泡菜品质的影响。结果表明,盐浓度为4.6%、糖浓度为4%、发酵温度为25℃,西瓜翠衣泡菜软硬适中、酸甜适口、泡菜风味最佳。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.